Electrochemical comparison of two sulfonated styrene PEM membranes synthesized by different methods

Abstract

The synthesis of two random copolymers was carried out by radical copolymerization. Poly(styrene-coacrylic acid) in a 94:6 (St:AA) molar ratio, partially crosslinked with trimethylol propane trimethacrylate was synthesized by mass polymerization and then sulfonated (PSAAS-m) with sulfuric acid. On the other hand, the same random PSAA was synthesized by solution polymerization, but cross-linked with divinylbenzene and then sulfonated (PSAAS-s). Copolymers, including non sulfonated controls, were dissolved in THF and used to coat a platinum (Pt) electrode by ''deep coating'' and studied electrochemically by the voltamperometric cycle technique in 0.5 M H 2 SO 4 . Both non-sulfonated PSAA copolymers showed only a baseline signal, indicating no proton conductivity through them. The same result was obtained for the PSAAS-s copolymer, suggesting no proton conductivity as well. On the contrary, the copolymer synthesized in mass and highly sulfonated (PSAAS-m) showed the corresponding signals of Pt reduction, similar to the experiment carried out for the Pt electrode without any coating. Ion exchange capacity and water uptake measurements support the electrochemical findings.

Sulfonated Binaphthyl-Containing Poly(arylene ether ketone)s with Rigid Backbone and Excellent Film-Forming Capability for Proton Exchange Membranes

“…However, it suffers from several drawbacks such as severe fuel permeation and high cost [5]. Therefore, lots of works have been devoted to the development of alternative PEMs, including sulfonated polystyrenes [6,7,8], sulfonated poly(arylene ether)s [9,10,11,12], sulfonated poly(arylene thioether)s [13,14], sulfonated poly(ether amide)s [15], sulfonated polyimides [16,17], sulfonated polybenzimidazoles [18], and sulfonated poly(phthalazinone ether)s [19,20]. Among them, sulfonated poly(arylene ether)s have been widely researched because of their good film-forming capability, robust mechanical strength, high thermal stability, and tunable proton conductivity [3,5].…”